double displacement 2

 Certainly, Mayank. Here's a clear, empathetic, and CBSE-exam–friendly explanation of the Double Displacement Reaction, designed for Class 10 Science students. It avoids humour and focuses on clarity, concept-building, and exam preparation.

🔄 Double Displacement Reaction

(Chapter 1: Chemical Reactions and Equations – Class 10 Science)

📘 Definition:

A double displacement reaction is a type of chemical reaction in which two compounds react by exchanging ions to form two new compounds.

✅ One of the new products is often a precipitate (insoluble solid), gas, or water.

🧪 General Reaction Format:

AB+CD→AD+CBAB + CD \rightarrow AD + CB

  • A and C are cations (positive ions)

  • B and D are anions (negative ions)

  • The ions are exchanged between the compounds

📌 Key Characteristics:

Feature Description
Reactants Two ionic compounds in aqueous solution
Process Exchange of ions between reactants
Products Usually includes precipitate, gas, or water
Common types Precipitation and Neutralization reactions

📘 Examples from the CBSE Class 10 Syllabus

✅ 1. Precipitation Reaction

(Solid formed as one product)

BaCl2(aq)+Na2SO4(aq)→BaSO4(s)+2NaCl(aq)\text{BaCl}_2 (aq) + \text{Na}_2\text{SO}_4 (aq) \rightarrow \text{BaSO}_4 (s) + 2\text{NaCl} (aq)

  • Barium sulphate (BaSO₄) is an insoluble white solid

  • This is a double displacement and a precipitation reaction

✅ 2. Neutralization Reaction

(Salt + water)

NaOH(aq)+HCl(aq)→NaCl(aq)+H2O(l)\text{NaOH} (aq) + \text{HCl} (aq) \rightarrow \text{NaCl} (aq) + \text{H}_2\text{O} (l)

  • Sodium hydroxide (base) reacts with hydrochloric acid

  • Produces salt (NaCl) and water

✅ 3. Reaction Producing Gas:

Na2CO3(aq)+2HCl(aq)→2NaCl(aq)+H2O(l)+CO2(g)\text{Na}_2\text{CO}_3 (aq) + 2\text{HCl} (aq) \rightarrow 2\text{NaCl} (aq) + \text{H}_2\text{O} (l) + \text{CO}_2 (g)

  • Carbon dioxide gas is released

  • It is both a double displacement and gas-evolution reaction

🧠 CBSE Exam Tip:

Q: Define double displacement reaction. Give one example with a balanced chemical equation.

✅ Answer:
A double displacement reaction is a chemical reaction in which two compounds exchange ions to form two new compounds, one of which may be a precipitate, gas, or water.

Example:

BaCl2(aq)+Na2SO4(aq)→BaSO4(s)+2NaCl(aq)\text{BaCl}_2 (aq) + \text{Na}_2\text{SO}_4 (aq) \rightarrow \text{BaSO}_4 (s) + 2\text{NaCl} (aq)

📝 How to Identify a Double Displacement Reaction:

  • Two aqueous ionic compounds are involved

  • A precipitate, gas, or water is formed

  • Ions are exchanged between reactants

🔚 Conclusion:

Double displacement reactions are important in real life (e.g., salt formation, water purification, medicine) and commonly asked in CBSE exams. Focus on:

  • Understanding ion exchange

  • Memorizing common examples

  • Practicing balanced chemical equations

Let me know if you’d like a concept map, quiz set, or worksheet to support this explanation in your classroom.

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